Should the muezzin repeat the call to prayer via loudspeaker after the electricity returns, or is the initial call to prayer, which was made without the loudspeaker, sufficient?

If a power outage led to people not hearing the adhan, then the adhan should be repeated. However, if other mosques have already called the adhan and people heard their adhan, then the adhan should not be repeated, because the objective of informing people about the entry of the prayer time has already been achieved.